Cathode sleeve



CATHODE SLEEVE Charles L. Taylor, Owensboro, Ky., assignor to General Electric Company, a corporation of New York Filed Nov. 18, 1957, Ser. No. 696,986

Claims. (Cl. 313-270) This invention relates to indirectly-heated cathodes for electron discharge devices, and more particularly to sleeves for such cathodes having tabs formed integrally therewith.

An object of the invention is to provide an integraltab cathode sleeve that resists longitudinal movement relative to the insulating spacers in which the sleeve is supported.

Another object is to provide an integral-tab cathode sleeve in which the tab functions as an electrical connector and simultaneously to lock the sleeve against mechanical movement or vibration.

To the attainment of the foregoing objects, I provide, in a preferred form, an integral-tab cathode sleeve in which the tab-end of the sleeve is longitudinally slit on each side of the tab and for a distance from the sleeve end substantially equal to the length of the projecting part of the sleeve beyond the spacer. The sleeve is provided with a bead or other stop that overlies a surface of the spacer. Thus, after the sleeve is inserted in the spacer with the bead in contact with the one surface of the spacer, the tab can be bent or folded outwardly from the sleeve, the bend or fold occurring at the opposite surface of the spacer. In this manner locking of the sleeve in the spacer is readily accomplished. In another form, wherein a contact tab integral with the sleeve is unnecessary or undesired, a locking tab is adapted, on being bent or folded outwardly of the sleeve, to be threaded through a suitably formed hole in the spacer and thereafter again folded to lie flush against the opposite surface of the spacer, thus to securely fasten the sleeve in place.

Other objects, features and many of the attendant advantages of this invention will be appreciated more readily as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings, wherin like parts in each of the several figures are identified by the same reference character, and wherein:

Figure 1 is an elevational view of an electron discharge tube, with parts broken away, and in which a cathode sleeve according to the invention is employed;

Figure 2 is an enlarged elevational view of a part of the sleeve shown in Figure 1;

Figure 3 is a perspective view of a portion of the novel cathode sleeve;

Figure 4 is a fragmentary view of a modified form of cathode sleeve according to my invention;

' Figure 5 is an elevational view of the sleeve of Figure 4 as assembled, and

Figure 6 is a perspective view of another modification.

As an illustration of one field of application of the cathode sleeve of this invention, there is shown in Figure 1, an electron discharge tube 11, comprising an envelope 13 containing an electrode assembly including an indirectly heated cathode 15, heater 16, grids 17 and 19, and anode 21 supported between spacers 23 and 25 respectively. Electrical connections of the anode 21, grids 17 v United States Patent 0 and 19, and heater 16 to selected contact pins 27 are made through stem leads 29 in any suitable conventional manner.

In one embodiment, the cathode sleeve of this invention, as shown more clearly in Figures 2 and 3 may comprise a tubular member 31, which may be of circular cross sections, as shown, or if desired may be of rectangular, oval, or any other cross-sectional configuration. The member may be fabricated with a lock seam 33, as illus trated, or, if desired can be formed with a butt or lap seam or may be seamless.

The tubular member 31 is preferably formed with a raised boss, bead or other stop 35 on the outer surface and at a distance from either end, here shown as the lower end of the member 31, such that when the sleeve is operatively positioned in the spacers 23, and 25-, the stop 35 rests on the one side of the spacer 25.

The member 31 is provdied at its lower end with an integrally formed tab 37 which, if desired, may be diamerally opposed to the seam 33. As seen more clearly in Figures 2 and ,3, the tab 37 is formed integrally with the member 31 and in unassembled form, extends axially a predetermined distance beyond the lower end of the member 31. To facilitate sleeve-locking action in relation to the spacer 25, a pair of slits 39 and 41 are made in the lower side of the member 31, one on each side of the tab 37, the slits extending along substantially parallel lines axially of the member 31 and for a distance there along so that on outward bending of the tab, after insertion in the spacer 25, the fold or bend portion 43 bears tightly against the side of the spacer opposite the beadabutting side. Bending or folding the tab 37 has the effect of altering the curvature of the tab at the bend or fold 43 from a generally convex surface generally conforming to that of the sleeve itself to a fiat surface as viewed in elevation. This, it will be appreciated, efiectively provides for increased rigidity of the tab at the bend portion. Having thus locked the sleeve 15 against undesired vibration, the free end of the tab 27 can be connected to a pin 29 in suitable manner as by spot welding.

It will, of course, be understood that while the foregoing description discloses my tab as being formed adjacent the lower end of the cathode sleeve, if desired, the tab can be disposed adjacent the upper end of the sleeve for connection of the cathode through a top-cap seal of the envelope 13 or to a lead to the stemor to one or more other elements.

In applications wherein elongated tabs are not required or desired, an integral tab fastener can be provided, in accordance with my invention, as shown in Figures 4 and 5. In this form, the end portion of a tubular sleeve member 45 is slit along spaced parallel lines axially of the member 45 as at 47 and 49, thus defining a tab 51. It will be noted that the tab can be preformed in such manner as to define an angular projection offset from the side of member 45. The extent of the off-set portion 53 is preselected to permit the vertically extending part of the tab 51 to thread an opening 55 formed in the spacer 57 adjacent the main opening for receiving the member 45. With the member 45- thus inserted in the main opening and the tab in the auxiliary opening 55, the off-set portion 53 lies flush along the surface of the spacer 57. Thereafter the part of the tab projecting through the spacer can be readily bent to lie flush along the other spacer surface, thus securely fastening the member 45 in position and against axial vibration. In the embodiment of Figures 4 and 5 no preformed bead or boss is needed, the off-set portion 53 performing the function thereof.

Another modified form of integral tab sleeve is shown in Figure 6, wherein the member 59 is provided with tapered slots 61, 63 to define the tab 65. I have found that such slots are somewhat simpler to form as by punching resulting in reduced cost of manufacture and/ or ease of assembly in spacer. The sleeve of Figure 6, in all other respects can be utilized in the manner described above in connection with the embodiment of Figures 2 and 3.

It will thus be seen that I have provided a novel integral-tab cathode sleeve that embodies several important advantages in that a combined integral electrical connector and sleeve-locking means is realized in a unitary structure. The tab of this invention, by the introduc tion of a flattened surface at the region of the bend, is characterized by increased stiffness at that region, thereby enhancing the vibration-minimizing function of the lock. The foregoing advantages are realized without virtually any increase in cost of manufacture of the part and actually results in a substantial saving in assembly costs by reducing the number of welds or other fastening operations normally required.

What I claim as new and desire to secure by Letters Patent is:

1. In combination, a tubular cathode, a pair of spacers having registering openings for receiving said cathode, a stop on said cathode, engaging one surface of one of said spacers, said cathode being formed with slits from the end thereof opposite said one surface to a point spaced from said stop not more than an amount corresponding to the thickness of said one spacer to provide an integral tab for said cathode, said tab being bent outwardly at' said point and rigidly engaging the surface opposite said one surface of said one spacer, thereby to lock said cathode in position relative said one spacer.

2. The combination as claimed in claim '1, wherein said cathode is cylindrical and the rigidity of said engagement 4 of said spacer by said tab is enhanced by the transition of said tab from an arcuate cross-section to a flat crosssection at the point of bend.

3. A sleeve for indirectly heated cathodes, comprising a cylindrical member, an embossment adjacent one end of said member, an integral tab formed at said one end of said member and projecting therebeyond, portions of said member adjacent said tab being slotted at the opposed edges of said tab to define with said tab tapered cutouts extending from said one end of said member to points spaced predeterminedly from said embossrnent.

4. The sleeve as defined in claim 3, wherein said cutouts are of decreasing circumferential dimension in a direction toward said embossinent.

5. A sleeve for an indirectly heated cathode comprising a cylindrical member, an embossment adjacent one end of said member, an integral tab formed at said one end of said member and projecting therebeyond, and said member including a pair of slits each on a side of said tab and extending longitudinally a predetermined distance toward said embossment.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Higgs Abstract of Abandoned Appl. Ser. No. 22,347, filed Apr. 21, 1948, published Aug. 3, 1949. 

